Machine for fine grading



May l, 1934- s. A. scuLLEN 1,956,931

MACHINE FOR FINE GRADING Filed Feb. 21, 1950 l 2 Sheets-Sheet lhws/vrai? /ee/ Jaa//e/P Arran/Vey May l, 1934- s. A. scULLEN MACHINE FORFINE GRADING Filed Feb. 21. 1930 2 Sheets-Sheet 2 NQQ e@ @0 O@ @O/A/vE/vrok 47' rok/v5 Y WN Nw N MVA J o H W. @m NN @w w I @D mw, l Q NM.HMM. %N N\%\ .Patente t'iay l, i934 li/IACHINE FR MNE GRADING 7 Claims.

IViy invention relates to road grading machinery and particularly to amachine for milling the subgrade of a concrete pavement to a precisegrade or elevation preparatory to laying the pavement thereon; thisapplication being a continuation in part of my application Serial No.293,010, led July 16, 15328.

In the preparation of the subgrade for a concrete pavement it isextremely important to the lo contractor that it be brought to theprecise grade and cross-section required by the plans. The plans andspecification for such pavements a ways prescribe a certain minimumthickness of concrete, the upper surface of which must be laid to aprecise grade or elevation, but it is of little moment to the State,municipal corporation or other employing party if the contractor lays apavement which is thicker than the prescribed minimum. However, onaccount of the high cost of materials going into a pavement of thischaracter, any increase in thickness over the prescribed minimum is asource of great loss to the contractor. l

lt is therefore customary to rough grade the subgrade, set the sideforms to precise grade, and then ne grade the subgrade between the formsand ahead of the mixer by hand. Grading in this way, by hand labor, isnot only very slow and very expensive by reason of the direct cost of3c` doing it, but is also very costly to the contractor where thefinished subgrade is even as little as a quarter or a half inch lowerthan that absolutely necessary to provide the prescribed minimumthickness oi concrete. On a foot road, for u example, if the subgradeaverages one-quarter of an inch too low the excess concrete required permile is about 122 cu. yds. and, if the subgrade is one-half an inch toolow the eXtra concrete yardage is, of course, double this. It is verydifficult, even with the most careful workmen, to fine grade thesubgrade to the precise elevation required, and in all cases where theoperations of the contractor are closely supervised by an engineer orinspector the subgrade is low.

The principal object, therefore, of my invention is to provide a meansfor ne grading the subgrade of a concrete road or the like so that itwill be brought to the precise grade required to give the minimum slabthickness prescribed. Another object is to provide a machine which willperform itswork quickly and cheaply and in which the material removedwill be deposited outside of the forms. Another object is to provide amachine of this character which will prepare a subgrade of any desiredtransverse crosssection, that is, bank the subgrade on curves, or cutthe subgrade to any required crown.

With these objects in View my invention includes the novel elements andthe combinations 6c and arrangements thereof described below andillustrated in the accompanying drawings, in which- Fig. 1 is a planview of my machine;

Fig. 2 is a side view thereof;

Fig. 3 is a fragmentary detail of a cutter for crowning the subgrade;and

Fig. 4 is a detail elevation View oi the conveyor reversing mechanism.

Generally speaking, my machine comprises a mechanism supporting framewhich is mounted on flanged wheels adapted to ride upon the side formsas rails. The element which performs the ne grading is a comparativelysmall diameter high speed milling cutter which extends transverselyacross the subgrade between the forms, and which turns in such adirection as to throw the out material ahead of itself and away from thenished grade. The milling cutter, on account of its high rotative speed,and on account of the slow rate at which it is automatically fed intothe material to be out reduces this material to a very ne dust which isprojected ahead of the cutter upon a conveyor extending transversely ofthe machine and adapted to dump the material outside of either side ofthe form.

Referring to the drawings for a more particular description of mymachine, 1 is a frame of angle irons or other suitable structural shapesforming a general support for the mechanism. This frame is mounted uponaxle, 2, at the rear of the machine and axle, 3, at the front, and theseaxles carry the flanged wheels, 4, adapted to ride on the side forms, 5.Supported upon the frame, 1, is an internal combustion engine, 6, whichserves, not only to move the machine along the side forms and thus feedthe cutter into the work but also serves as a source of power fordriving the cutter and the conveyor. The manner in which the engine, 6,is connected to the axle shaft, 2, and to the cutter bar and conveyor isnot important although it is desirable that the drive be positive andthe gearing be such that the cutter bar is turned at about 80G R. P. M.and that it be fed into the material to be removed at a rate of only 3or l 105 feet a minute.

1n the drawings, I have shown a sprocket wheel,

7, mounted upon the engine shaft. This sprocket drives the transverseshaft, 8, mounted in suitable bearings on frame, l, by means of thechain,

9. Mounted upon the shaft, 8, is the small sprocket, 10, driving chain,11, running over a large sprocket wheel, 12, mounted on transverseshaft, 13, near the rear of the machine. The transverse shaft, 13, ismounted in suitable bearings on the frame, l, and has loosely mountedthereon the bevel pinions, 14 and 15, both of which are in mesh with alarger, master gear, 16, mounted on shaft, 17. Clutches, 13 and 19, areprovided in connection with the bevel pinions, 14 and 15, through themedium of which either pinion, 14, or pinion, 15, may be positivelyconnected to the shaft, 13, and be driven thereby. The clutches, 18 and19, are operated together by means of the handle, 20, so that whenpinion, 14, is connected to sha-ft, 13, pinion, 15, is disconnected andvice versa. This provides the necessary mechanism for reversing themovement of the machine along the side rails.

At 21, I have shown a speed reducing mechanism which may, for example,be in the ratio of 205 to 1. That is, if the shaft, 17, turns 230revolutions per minute the shaft, 2, which drives the rear wheels, 4,will turn only once a minute. Whatever gearing arrangement is usedbetween the engine, 6, and the rear driving wheels, 4, the ratio shouldbe such that when the engine is running at normal speed the machine willbe moved along the rails at a comparatively low rate of speed, say 3 or4 feet per minute.

There is also mounted upon shaft, 8, a sprocket, 22, driving chain, 23,running over a sprocket, 24, on the shaft of the milling cutter, 44. Theratio of the gearing here should be such that when the engine is runningat normal speed and the entire machine is being driven along the railsat 3 or 4 feet per minute the cutter will be turned at comparativelyhigh speed, say about 800 R. P. M.

This milling cutter is of comparatively small diameter and preferably,but not necessarily, comprises a square bar, about 4 inches on the side,which is mounted in suitable bearings on the frame, 1, and extendstransversely across the machine practically to the inside of the formson each side. In any event the cutter bar obviously should extend justas close to the inside of the forms as is possible. Mounted upon thissquare bar are the slightly spaced knives, 25, forming substantiallycontinuous cutting edges extending transversely across the subgrade.These cutting edges are preferably made up of a plurality of separateunits or knives each secured to the bar by means of bolts or cap screws,26, and having the rear edge of each unit abutting against the side ofan element on an adjacent side of the square bar. The free ends of theseelements extend a short distance only beyond the shaft on which they aremounted, and preferably a distance which is less than the diameter ofthe shaft itself, in order that the elements may withstand the severeusage to which they are subjected. 'Ihese separate elements which go tomake up the cutting edge are quite closely spaced as shown in Fig. 1,and the separate elements on the different sides of the shaft may bestaggered as shown. There are two reasons why the cutting edges arepreferably formed in this way. One of these reasons is because if one ofthe smaller elements is broken or nicked it may be readily replacedwithout replacing the entire cutting edge extending across the machine.Another reason is because it permits different lengths of cuttingelements to be applied at different parts of the milling cutter so thatthe device may be necaesl adapted to cut a crowned or other specifiedsubgrade.

The bearings at each end of the milling cutter and in which it issupported may be raised or lowered independently of each other by meansof suitable adjusting devices, 27, so that the cutting element may planethe subgrade to a transverse slope where required.

Just in front of the cutter is a conveyor, represented generally by thenumeral, 28, which extends transversely of the machine and somewhatbeyond the side forms as shown in Fig. 1. rThis conveyor preferablyconsists merely of a horizontal plate, 29, supported from the frame, 1,at an elevation just above the top of the side forms and across whichare dragged a plurality of bars or scrapers, 30, connected to thechains, 31. These chains extend over sprockets, 32 and 33, at one sideof the machine and the sprockets, 34 and 35, at the other end of themachine. Sprockets, 34 and 35, are connected to shaft, 36, mounted inbearings, 37, on frame, 1, and sprockets, 32 and 33, are connected toshaft, 38, supported in bearings, 39, secured to the frame.

It is desirable that the conveyor' should be reversible so that materialmay be carried to either side of the road bed. Loosely mounted on shaft,38, are two bevel pinions, and 4S, both of which are in mesh with bevelgear, 47, on vertical shaft, 43. The shaft, 48, at the upper end, hasmounted thereon a bevel pinion, 49, which meshes with pinion, 50, onshaft, 51, extending transversely across the frame and which is drivenby sprocket wheel, 52, and chain, 53, running over sprocket, 54, ondriven shaft, 13. The pinions, 45 and 46, are provided with clutches, 55and 56, respectively, which operate in substantially the same way asclutches, 13 and 19, on shaft, 13. These clutches are actuated togetherby lever, 57, (see Fig. 1). When lever, 57, is pushed in one direction,pinion, 45, for example, is secured to shaft, 38, through the clutchmechanism, 55, and pinion, 46, is disengaged from shaft, 38, by means ofclutch mechanism, 56. When the lever, 57, is pushed in the reversedirection, pinion, 46, is secured to shaft, 38, by means of clutchmechanism, 56, and pinion, 45, is disengaged. Thus, the conveyor may bedriven in either direction.

In operation, my machine is mounted upon the side forms as shown in thedrawings and is disposed ahead of the mixer which is laying theconcrete. It is propelled slowly along the forms (at 3 or 4 feet perminute) and the milling cutter is adjusted to cut the subgrade to theprecise elevation by means of the elevation regulating devices, 27. Themilling cutter revolves very rapidly (around 800 R. P. M.) in thedirection of the arrow shown in Fig. 2. On account of this comparativelyhigh rotative speed the material of the subgrade with which it is slowlybrought into contact is reduced to a comparatively fine dust which isprojected forwardly, upwardly and away from the milling cutter. Toprevent the material from being thrown upwardly and to insure its beingprojected forwardly upon the conveyor, I provide over the millingcutter, a suitable hood or defiector, 40, as shown in Fig. 2. The sideof the conveyor adjacent the milling cutter' in provided with an apron,41, which is hinged to the conveyor plate, 29, at 42. The lower edge ofthis apron, 41, or dust pan drags along on the subgrade and forms aninclined surface up and over which the material is thrown by the millingcutter onto the conveyor. Suitable means, 43, may be provided forraising the apron or dust pan and securing it in raised position when itis desired to move the machine backwardly.

From the foregoing it will be apparent that I have provided a devicewhich will precisely plane the subgrade of a concrete road far moreaccurately, more quickly and cheaper than it can be done by hand. Iconsider it quite essential that the cutting element be of comparativelysmall diameter and that it be rotated at comparatively high speed. Inother words, my cutting element does not function as a digging elementor as a scarifying element, but functions very much like a millingcutter on a milling machine.

i It is quite essential too that the cutter rotate in the directionshown, that is, in such a direction that it will throw the materialahead thus leaving the subgrade over which the milling cutter hasalready passed in perfect condition.

While I have described my invention in its preferred embodiment it is tobe understood that the drawings are merely illustrative, that the wordswhich I have used are words of description rather than of limitation,and that changes, within the purview of the appended claims, may be madewithout departing from the true scope and spirit of my invention in itsbroader aspects.

What I claim is:

l. In a machine for milling to precise elevation the surface of thesubgrade for a pavement, a wheeled frame, a rectangular cutter shaftthereon, means for independently adjusting the respective ends of thecutter shaft with respect to the frame, a plurality of cutting bladessecured in spaced relation on each side of the shaft, the blades on oneside being offset longitudinally of the shaft with respect lo the bladeson the adjacent side and bridging the space between the blades on suchadjacent side, the cutting edges of the blades extending beyond the nthe surface of the subgrade for a pavement, a

wheeled frame, a rectangular cutter shaft thereon, means forindependently adjusting the respective ends of the cutter shaft withrespect to the frame, a plurality of cutting blades secured in spacedrelation on each side of the shaft, the blades on one side being offsetlongitudinally of the shaft with respect to the blades on the adjacentside and bridging the space between the blades on such adjacent side,the cutting edges of the blades extending beyond the periphery of theshaft at one end, the heel end of each blade abutting squarely againsttwo blades on the adjacent side of the shaft, means for operating theshaft in a direction to cause the cutting action of the blades to exerta lifting infiuence on the material cut, and means carried by the frameto receive the raised material for delivery beyond the road-bed.

3. A machine for milling to precise elevation the surface of thesubgrade for a pavement comprising a frame, wheels carrying said frameand adapted to roll on the side forms for said pavement, means forpropelling said device at a comparatively slow rate of speed, a millingcutter of comparatively small over all diameter extending transverselyof said frame but comprising a shaft cf comparatively large size havinga plurality of peripherally spaced cutting edges thereon projecting buta comparatively small distance from the exterior of said shaft wherebysaid milling cutter and the cutting edges thereof are endowed with greatstrength and resistance to flexure, means for raising and lowering eachend of said cutter independently of the other, and means for rotatingsaid cutter at a high speed adapted to impart thereto a velocity ofattack on outcroppings of rock and the like sufficient to fracture andpulverize the same.

e. A machine for milling to precise elevation the surface of thesubgrade for a pavement comprising a frame, wheels carrying said frameand adapted to roll on the side forms for said pavement, means forpropelling said device at a comparatively slow rate of speed, a millingcutter of comparatively small over all diameter extending transverselyof said frame but comprising a shaft of comparatively large size havinga plurality of peripherally spaced cutting edges thereon projecting buta comparatively small distance from the exterior of said shaft wherebysaid milling cutter and the cutting edges thereof are endowed with greatstrength and resistance to flexure, means for raising and lowering eachend of said cutter independently of the other, means for rotating saidcutter at a high speed adapted to impart thereto a velocity of attack onoutcroppings of rock and the like sufficient to fracture, pulverize andproject the cut particles thereof forwardly in the direction in whichthe machine is moving, and a movable conveyor extending transversely ofsaid machine in front of said milling cutter arranged to catch theparticles projected from said cutter.

5. The structure set forth in claim 3 in which the speed at which themilling cutter is driven is in excess of 600 R. P. M.

6. The structure set forth in claim 4 in which the speed at which themilling cutter is driven is in excess of 600 R. P. M.

'7. The structure set forth in claim 3 in which the peripherally spacedcutting edges comprise a multiplicity of separate but closely spacedelements arranged in rows extending longitudinally of the cutter; saidelements being removably secured to said shaft whereby nicked or brokenelements of the cutting edges may be readily replaced.

STEPHEN A. SCULLEN.

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